21241781555 has 8 divisors (see below), whose sum is σ = 25500822000. Its totient is φ = 16986302496.

The previous prime is 21241781551. The next prime is 21241781573. The reversal of 21241781555 is 55518714212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21241781555 - 2² = 21241781551 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21241781551) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 877205 + ... + 901094.

It is an arithmetic number, because the mean of its divisors is an integer number (3187602750).

Almost surely, 2^21241781555 is an apocalyptic number.

21241781555 is a deficient number, since it is larger than the sum of its proper divisors (4259040445).

21241781555 is a wasteful number, since it uses less digits than its factorization.

21241781555 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1780693.

The product of its digits is 112000, while the sum is 41.

The spelling of 21241781555 in words is "twenty-one billion, two hundred forty-one million, seven hundred eighty-one thousand, five hundred fifty-five".